WattMaster Water Source Heat Pump, Installation & Operation Manual

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Section 2 WattMaster WHP
2-10 Installation and Wiring
Supply & Return Water
Temperature Sensors
Sensors for monitoring supply and return water temperature are available in two main
types, fluid immersion temperature sensors (See Figure 2-6) and strap-on sensors (See
Figure 2-7). Both are 0-10000 ohm thermistor type sensors. The fluid immersion sensor
generally has better accuracy than the strap-on type but either is suitable for typical water
source heat pump temperature requirements. The fluid immersion type sensor requires
that a thermowell be installed in the pipe and the strap-on type, as its name implies,
simply straps around the outside of the pipe. The fluid immersion sensor requires that the
pipe be at least 4” in diameter in order to accept the thermowell. The strap-on type sensor
is adjustable for use on 1/2” to 6” or larger diameter pipe.
The fluid immersion sensor is provided with a 4” long stainless steel thermowell. It has
½” MPT external threads and ½” FPT internal threads. A ½” FPT fitting to accept the
thermowell must be provided by others in the pipe to be monitored, for connection of the
thermowell. The thermowell is screwed into the ½” FPT fitting installed by others in the
pipe and the sensor probe is then screwed into the ½” FPT fitting on the thermowell.
1/8-27 NPSM Internal Thread
1/8-27 NPT External Thread
1/2" NPT External Thread
3.25
0.5
5.13
5.50
4.94
OE291 Stainless Steel Thermowell
OE230 Duct Sensor
Leads Are Non-polarized.
Butt Splice Leads To 24 Gauge
Wire Minimum. Connect Leads
To "Analog In" And "Ground"
At Controller.
The OE230 Duct Sensor Threads Into The OE291 Stainless
Steel Thermowell. The OE291 Thermowell Threads Into A 1/2”
FPT Elbow or Tee in the Water Piping of the Water Coil
Where You Wish to Measure the Water Temperature. The
Pipe must be a minimum of 4” Diameter or an Extended Tee
and Bushing Configuration Must be Used to Accommodate the
Length of the Thermowell Assembly.
Figure 2-6: Duct Sensor with Thermowell